Comment 3 for bug 579804

If we do decide to keep tags up to date in photo files, we will absolutely update them via a background task: we certainly don't want to make users wait while that happens! :)

There's another question here: if we do keep tags in photo files, we need to decide whether to update master photo files when photos are tagged, or to create a modified copy of each master solely for the purpose of holding the tags, even if there are no changes to the image itself. It seems wasteful to copy the files just to hold tags: this will double the library size if every file is tagged. But, again, some users might think that the master files are sacred and might not want even tags written there.